Date: Sun, 28 Apr 2024 21:33:45 +0200 From: Dirk-Willem van Gulik <dirkx@webweaving.org> To: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Multicast & Tunnel devices Message-ID: <D00CB346-F704-4111-8C7B-648EFA8A8C89@webweaving.org>
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Would anyone know if there is something special with tunnel devices and =
multicast ?=20
I=E2=80=99ve got some code that happily processes multicast packets on a =
normal interface; but appears not to do this on a tunnel interface. Tun0 =
shows multicast enabled:
=09
tun0: flags=3D8043<UP,BROADCAST,RUNNING,MULTICAST> metric 0 mtu =
1500
Tcpdump on that interface gives the expected thing (here with mDNS):
tcpdump -n -i tun0 port 5353
listening on tun0, link-type NULL (BSD loopback), capture size =
262144 bytes
19:26:03.976259 IP 10.31.0.6.5353 > 224.0.0.251.5353: 0 PTR =
(QM)? _raop._tcp.local. (34)
And code, with a simple IP_ADD_MEMBERSHIP of the MC group on the IP of =
the local interface below works on a normal interface (e.g. =
igb0/10.0.0.1/24).=20
./listener 10.0.0.1 224.0.0.251 5353
Received packet, len=3D128
etc
But yields no output if ran against above tun0 interface (while tcpdump =
on same is fine). Does that ring a bell with anyone ?
Dw
int main(int argc, char *argv[])
{
struct sockaddr_in addr;
struct ip_mreq mreq;
// skip error trapping command line arguments
char* ip =3D argv[1];=20
char* group =3D argv[2];=20
int port =3D atoi(argv[3]); // 0 if error, which is an invalid port
memset(&addr, 0, sizeof(addr));
addr.sin_family =3D AF_INET;
addr.sin_addr.s_addr =3D htonl(INADDR_ANY);
addr.sin_port =3D htons(port);
mreq.imr_interface.s_addr =3D inet_addr(ip);=20
mreq.imr_multiaddr.s_addr =3D inet_addr(group);
// skip error trapping on inet_addr
int fd =3D socket(AF_INET, SOCK_DGRAM, 0);
// skip error trapping socket
if (bind(fd, (struct sockaddr*) &addr, sizeof(addr)) < 0) {
// skip error trapping
if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*) &mreq, =
sizeof(mreq)) < 0 ){
// skip error trapping argumetns
while (1) {
..
int nbytes =3D recvfrom(fd,msgbuf,MSGBUFSIZE,0,(struct sockaddr =
*) &addr,&addrlen);
if (nbytes < 0) {
perror("recvfrom");
return 1;
}
printf(=E2=80=9CReceived packet, len=3D%d\n", nbytes);
}
--Apple-Mail=_2C77F2BB-87C7-4F5B-A2B8-5CD33CED02FF
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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;">Would anyone =
know if there is something special with tunnel devices and multicast =
? <div><br></div><div>I=E2=80=99ve got some code that happily =
processes multicast packets on a normal interface; but appears not to do =
this on a tunnel interface. Tun0 shows multicast enabled:<div><span =
class=3D"Apple-tab-span" style=3D"white-space:pre"> =
</span></div><div><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span><span style=3D"font-family: =
Menlo; font-size: 11px;">tun0: =
flags=3D8043<UP,BROADCAST,RUNNING,MULTICAST> metric 0 mtu =
1500</span></div><div><span style=3D"font-family: Menlo; font-size: =
11px;"><br></span></div><div><font face=3D"Menlo"><span =
style=3D"font-size: 11px;">Tcpdump on that interface gives the expected =
thing (here with mDNS):</span></font></div><div><font face=3D"Menlo"><span=
style=3D"font-size: 11px;"><br></span></font></div><div><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span>tcpdump -n -i tun0 port =
5353</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span>listening on tun0, link-type NULL =
(BSD loopback), capture size 262144 bytes</p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span>19:26:03.976259 IP 10.31.0.6.5353 =
> 224.0.0.251.5353: 0 PTR (QM)? _raop._tcp.local. (34)</span></p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"><br></span></p><p style=3D"margin: 0px; font-style: =
normal; font-variant-caps: normal; font-stretch: normal; font-size: =
11px; line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
style=3D"font-variant-ligatures: no-common-ligatures">And code, with a =
simple </span>IP_ADD_MEMBERSHIP of the MC group on the IP of =
the local interface below works on a normal interface (e.g. =
igb0/10.0.0.1/24). </p><p style=3D"margin: 0px; font-style: normal; =
font-variant-caps: normal; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
style=3D"font-variant-ligatures: no-common-ligatures"><br></span></p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span>./listener </span>10.0.0.1 =
224.0.0.251 5353</p><p style=3D"margin: 0px; font-style: normal; =
font-variant-caps: normal; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre"> </span>Received =
packet, len=3D128</p><p style=3D"margin: 0px; font-style: normal; =
font-variant-caps: normal; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre"> </span>etc</p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><br></p><p style=3D"margin: 0px; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
style=3D"font-variant-ligatures: no-common-ligatures;">But yields no =
output if ran against above tun0 interface (while tcpdump on same is =
fine). Does that ring a bell with anyone ?</span></p><p style=3D"margin: =
0px; font-stretch: normal; font-size: 11px; line-height: normal; =
font-family: Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
style=3D"font-variant-ligatures: no-common-ligatures;"><br></span></p><p =
style=3D"margin: 0px; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures;">Dw</span></p></div><div><span =
style=3D"font-variant-ligatures: =
no-common-ligatures;"><br></span></div><div><span =
style=3D"font-variant-ligatures: =
no-common-ligatures;"><br></span></div><div><span =
style=3D"font-variant-ligatures: no-common-ligatures;"><p style=3D"margin:=
0px; font-style: normal; font-variant-caps: normal; font-stretch: =
normal; font-size: 11px; line-height: normal; font-family: Menlo; =
font-size-adjust: none; font-kerning: auto; font-variant-alternates: =
normal; font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
style=3D"font-variant-ligatures: no-common-ligatures">int main(int argc, =
char *argv[])</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures">{</span></p><p style=3D"margin: 0px; font-stretch: =
normal; font-size: 11px; line-height: normal; font-family: Menlo; =
font-size-adjust: none; font-kerning: auto; font-variant-alternates: =
normal; font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"> struct sockaddr_in =
addr;</p><p style=3D"margin: 0px; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures;"> struct ip_mreq =
mreq;</span></p><p style=3D"margin: 0px; font-style: normal; =
font-variant-caps: normal; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><br></p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span class=3D"Apple-tab-span" =
style=3D"white-space: pre;"> </span>// skip error trapping command =
line arguments</p><p style=3D"margin: 0px; font-style: normal; =
font-variant-caps: normal; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><br></p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"> char* ip =3D =
argv[1]; </p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> char* group =3D =
argv[2]; </span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> int port =3D atoi(argv[3]); // 0 if =
error, which is an invalid port</span></p><p style=3D"margin: 0px; =
font-style: normal; font-variant-caps: normal; font-stretch: normal; =
font-size: 11px; line-height: normal; font-family: Menlo; =
font-size-adjust: none; font-kerning: auto; font-variant-alternates: =
normal; font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><br></p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> memset(&addr, 0, =
sizeof(addr));</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> addr.sin_family =3D =
AF_INET;</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> addr.sin_addr.s_addr =3D =
htonl(INADDR_ANY);</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> addr.sin_port =3D =
htons(port);</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal; min-height: 13px;"><span =
style=3D"font-variant-ligatures: no-common-ligatures"></span><br></p>
<p style=3D"margin: 0px; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures;"> mreq.imr_interface.s_addr =3D =
inet_addr(ip); </span></p><p style=3D"margin: 0px; font-style: =
normal; font-variant-caps: normal; font-stretch: normal; font-size: =
11px; line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-variant-emoji: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"> =
mreq.imr_multiaddr.s_addr =3D inet_addr(group);</p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><br></p><p style=3D"margin: 0px; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
class=3D"Apple-tab-span" style=3D"white-space:pre"> </span>// skip =
error trapping on inet_addr</p><div><br></div><p style=3D"margin: 0px; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-feature-settings: normal; =
font-optical-sizing: auto; font-variation-settings: normal;"><span =
style=3D"font-variant-ligatures: no-common-ligatures;"> =
int fd =3D socket(AF_INET, SOCK_DGRAM, 0);</span></p><p =
style=3D"margin: 0px; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span class=3D"Apple-tab-span" =
style=3D"white-space: pre;"> </span>// skip error trapping =
socket</p><div><br></div>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> if (bind(fd, (struct sockaddr*) =
&addr, sizeof(addr)) < 0) {</span></p>
<p style=3D"margin: 0px; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span class=3D"Apple-tab-span" =
style=3D"white-space: pre;"> </span>// skip error =
trapping</p><div><br></div>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> if (</span>setsockopt(<span =
style=3D"font-variant-ligatures: no-common-ligatures;">fd, IPPROTO_IP, =
IP_ADD_MEMBERSHIP, (char*) &mreq, sizeof(mreq)</span>) < 0 ){</p>
<p style=3D"margin: 0px; font-stretch: normal; font-size: 11px; =
line-height: normal; font-family: Menlo; font-size-adjust: none; =
font-kerning: auto; font-variant-alternates: normal; =
font-variant-ligatures: normal; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-position: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span class=3D"Apple-tab-span" =
style=3D"white-space: pre;"> </span>// skip error trapping =
argumetns</p><div><br></div>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> while (1) {</span></p><p =
style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span>..</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"> int nbytes =
=3D recvfrom(fd,msgbuf,MSGBUFSIZE,0,(struct sockaddr *) =
&addr,&addrlen);</p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> if (nbytes < 0) =
{</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> =
perror("recvfrom");</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> return =
1;</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"> }</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"><span style=3D"font-variant-ligatures: =
no-common-ligatures"><span class=3D"Apple-tab-span" =
style=3D"white-space:pre"> </span>printf(=E2=80=9CReceived packet, =
len=3D%d\n", nbytes);</span></p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal;"> }</p>
<p style=3D"margin: 0px; font-style: normal; font-variant-caps: normal; =
font-stretch: normal; font-size: 11px; line-height: normal; font-family: =
Menlo; font-size-adjust: none; font-kerning: auto; =
font-variant-alternates: normal; font-variant-ligatures: normal; =
font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-position: normal; font-variant-emoji: normal; =
font-feature-settings: normal; font-optical-sizing: auto; =
font-variation-settings: normal; min-height: =
13px;"><br></p></span></div></div></body></html>=
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